Patent GB-556739-A (GB)
Title: Improvements in or relating to electrical remote indicating and supervisory systems
IPC: H02J13/00
Filed: 1942-03-12
Abstract: 556,739. Electric selective signalling systems. STANDARD TELEPHONES & CABLES, Ltd., BOWSHER, E. A. H., FONSECA, H. M. M. D'ASSIS-, and WARD, H. J. March 12, 1942, No. 3258. [Class 40 (i)] In an electric signalling system for power supply networks, information concerning units such as circuit breakers is conveyed by a train of impulses, the condition of each circuit breaker being indicated by the polarity of an impulse and a change in condition by a lengthened impulse. When a circuit breaker OCB changes over it connects +<SP>ve</SP> battery to lead O or C to provide for the transmission of a +<SP>ve</SP> or -<SP>ve</SP> impulse, charges up one of a pair of condensers, -and leaves the other charged and isolated to provide the change indication. A permanent alarm condition on other equipment operates a relay such as ALA the change-over contacts ala1 of which operate in a similar manner to those of the breaker. A momentary alarm operates MLA which has similarly functioning change-over contacts and is locked up dependent on LLA. Control of the circuits and of the signals is effected by switch SS stepped under the control of a pendulum relay P1 and pairs of impulsing relays X, Y (for normal impulses) CX, CY (for lengthened impulses) and DX, DY (for extra long seizing &c. impulses). Banks SS1, SS2 are used for control of local circuits and the indications are given over pairs of banks SS 3, 4; SS 5, 6 ; SS 7, 8, connected up by switching relays HA, HB during successive complete revolutions. Sub-station makes a call.-When a change of condition or an alarm occurs, common relay LA is operated by the condenser charging operation described above, followed by S, which releases LA, and by ST slowly over wiper SS2 (normal). In the meantime, pendulum relay P1 has been operated and released and continues to swing at 20 c.p.s. Its impulsing contacts control X and Y in succession so that these relays operate at 10 c.p.s. and their operating periods extend over a full swing (to and fro) of the pendulum but are displaced by half the full swing period. Relay X controls, in a similar manner, dependent on the operation of CC, a further pair CX, CY operating at 5 c.p.s., and CX controls in positions 1 and 2 of the switch, a further pair DX, DT used for the production of a very long pulse. These relays are used to control the stepping circuit of the switch and also the holding circuits of PN, PP which respectively transmit negative and positive impulses over the line circuit, Fig. 1. This line circuit has a normally flowing weak "proving" current which is removed when S pulls up, LV being a relay normally operated in this battery supply circuit. After P1 has made a number of swings to operate and release the various X, Y relays in the proper combination to make and break the circuit of switch magnet SSM, SS steps to position 2 in which PN is operated over SS4 and held by Y, CY and DY over overlapping periods and finally by Z to send an extra long negative impulse as a calling signal. The next time X, CX are operated when DX is back, Z pulls up and locks followed by ZZ and the release of S whereupon all the impulse controlling relays are open-circuited. ST falls back, SS goes home and Z releases to terminate the pulse. ZZ falls back very slowly to hold open the line proving circuit until the equipment at the tandem station has restored. The substation circuit now awaits initiation of another call or a request for a supervisory cycle from the control station. Supervisory cycles.-The request, in the form of a long -<SP>ve</SP> pulse operates IN followed by CK which holds, brings up S and opens the circuits of Z, ZZ to prevent homing of SS after the partial revolution described on the preceding paragraph. When the pulse ceases, PI, ST operate as before but the extra long <SP>-ve</SP> pulse in position 2 is dependent on Y, DX, DY alone. When the pulse terminates SS steps to 3 and a normal <SP>-ve</SP> pulse is transmitted indicating the 1st revolution of the switch, which is now stepped by Y alone unless CC and CX are brought in due to occurrence of a change. In position 4, the substation battery voltage is signalled as standard by a lengthened negative or as low by a normal negative.. Relay LV, Fig. 1, is normally operated on standard voltage and brings in CC over SS3 to lengthen the <SP>-ve</SP> pulse produced by battery on SS4. Relay PP will not operate in series with CC. The remainder of the switch revolution deals with conditions of circuit breakers, alarms &c. The fixed springs of the change over contacts OCB, al a and so on are connected to contacts in banks SS1, 2 so that PN or PP is operated at each step to send a normal <SP>-ve</SP> or +<SP>ve</SP> impulse. If, however, a change has occurred, the charged and isolated condenser discharges over PN or PP (whichever is unoperated by the condition indication and which does not operate in this circuit), -<SP>ve</SP>, NG-, CC. Terminal NG- is connected to the corresponding terminal in Fig. 1 which provides a smoothed supply for the condenser circuits. Relay CC brings in the 5 c.p.s. pulsing pair CX, CY to lengthen the period during which SS remains stationary and so lengthening the pulse, +<SP>ve</SP> or -<SP>ve</SP>. When the switch reaches position 24, J operates over SS2 and when the last indication has been sent (position 25), the switch steps to position 1 in which switching relay HA connects PP, PN to the wipers of the next pair of banks SS5, SS6. Similar operations ensue during the next revolution except that (1) a normal -<SP>ve</SP> is sent in position 1 to keep the distant received in step, (2) a normal +<SP>ve</SP> is sent in position 3 to indicate the 2nd revolution, (3) there is no provision for a battery voltage signal, (4) JA pulls up over SS2 in position 22 so that switching relay 4B connects up wipers of banks SS7, SS8 when the switch next reaches position 1. The 3rd revolution produces the same results except for a long -<SP>ve</SP> in position 3 to indicate this revolution. and that JB operates in position 20 so that when the switch reaches position 2 in the 4th revolution and the extra long <SP>-ve</SP>  pulse is sent, Z pulls up followed by ZZ. Relays S,CK and ST fall back and switch SS homes. Faults. Continuous sending, due to failure of Z to operate, is prevented by an alternative circuit for Z closed by J, JA, JB during successive revolutions of the switch. Specifications 439,000, [Group XL], 514,991 and 556,745 are referred to.